Controlling emissions from a motor vehicle may reduce environmental pollution due to motor vehicle traffic. Emissions of particles, such as nitrogen oxide, may be reduced by mixing some of the exhaust gas formed during the combustion process of the engine with intake air provided to the engine. For example, low-pressure exhaust gas recirculation (EGR) may be provided to reduce nitrogen oxide emissions wherein exhaust gas is introduced downstream of the compressor. However, condensate may form in the exhaust gas during introduction of the exhaust gas to the intake air due to a temperature differential. The condensate may impinge on the compressor wheel of the compressor causing damage.
One example to address the condensate issue is to use high pressure EGR wherein the exhaust gas is introduced upstream of compressor.
However, the inventors herein have recognized potential issues with such systems. Using only high-pressure EGR may reduce the beneficial aspects of EGR.
One potential approach to at least partially address some of the above issues includes a system and method for a low-pressure EGR valve. The low-pressure EGR valve comprises a fresh air inlet, an exhaust gas inlet, an outlet which is connected to a compressor, and at least one throttling device. The at least one throttling device influences a fresh air quantity flowing through the fresh air inlet and an exhaust gas quantity flowing through the exhaust gas inlet. The low-pressure EGR valve may have a connecting surface situated between the outlet and the exhaust gas inlet. The connecting surface may be shaped in such a way that condensate flows from the outlet to the exhaust gas inlet during use of the low-pressure EGR valve as intended.
In one example, a connecting surface may be provided in a low-pressure EGR valve with a curve profile comprising an angle such that the condensate flows from the outlet to the exhaust gas inlet and thus prevents condensate from entering the compressor. The connecting surface curve profile may be such that the condensate overcomes any opposing forces which may prevent the condensate from flowing away from the outlet. In this way, it may be possible to reduce the effect of condensate while continuing to enable accurate control of EGR flow.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.